Introduction
All stages of the cystic fibrosis-related abnormal glucose tolerance (CF-AGT) spectrum are associated with increased morbidity and mortality which could be reduced by early detection and treatment (1-4). Despite, the oral glucose tolerance test (OGTT) with two blood glucose measurement time points from 10 years of age (yoa) is still the gold standard method according to current guidelines (5,6).
Aims & Methods
Our aim is to provide data on the usability and diagnostic value of a hybrid protocol for the detection of early AGT in children with CF (chwCF).
The Cystic Fibrosis Related Pancreatic Disorder Registry (CFRPDR) is a prospective registry involving chwCF (<18 yoa) undergoing our hybrid AGT-screening protocol. The screening protocol consists of a frequently-sampled three-hour OGTT with blood sampling in every 30 minutes. Those chwCF with more than two interim blood glucose levels higher than 11 mmol/l are further examined with postprandial capillary glucose monitoring. Screening is started as early as possible, in most cases before 10 yoa and repeated yearly.
Results
Currently 121 chwCF are involved in the registry from which we have analyzed the baseline data of the first 79. 74% of the chwCF were diagnosed with normal glucose tolerance (NGT) (0-18 yoa: 58, 0-6 yoa: 18, 7-12 yoa: 22, 13-18 yoa: 18), 15% with impaired glucose tolerance (IGT) (0-18 yoa: 12, 0-6 yoa: 3, 7-12 yoa: 5, 13-18 yoa: 4) and 11% with CF-related diabetes (CFRD) (0-18 yoa: 9, 0-6 yoa: 0, 7-12 yoa: 1, 13-18 yoa: 8) according to the current gold standard method. 60% of the chwCF were diagnosed with NGT (0-18 yoa: 47, 0-6 yoa: 14, 7-12 yoa: 17, 13-18 yoa: 16), 14% with indeterminate glycaemia (INDET) (0-18 yoa: 11, 0-6 yoa: 4, 7-12 yoa: 5, 13-18 yoa: 2), 15% with IGT (0-18 yoa: 12, 0-6 yoa: 3, 7-12 yoa: 5, 13-18 yoa: 4), and 11% with CFRD (0-18 yoa: 9, 0-6 yoa: 0, 7-12 yoa: 1, 13-18 yoa: 8) by frequently-sampled OGTT. After the postprandial capillary glucose monitoring 4 more diabetic chwCF were diagnosed, 3 of them had IGT and 1 of them had INDET according to their OGTT measurements. 39% (12 chwCF) of the AGT cases was diagnosed under 10 yoa with frequently sampled OGTT.
Conclusion
In our cohort CF-AGT is common even under 10 yoa, and 44% of the AGT cases would have been missed with current standard screening method. Therefore, guidelines need to be revised, and our hybrid AGT-screening protocol could be a potent alternative especially in low- and middle income countries where continuous glucose monitoring is less available.
References
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5. Moran A, Brunzell C, Cohen RC, Katz M, Marshall BC, Onady G, et al. Clinical care guidelines for cystic fibrosis-related diabetes: a position statement of the American Diabetes Association and a clinical practice guideline of the Cystic Fibrosis Foundation, endorsed by the Pediatric Endocrine Society. Diabetes Care. 2010;33(12):2697-708.
6. Balfour-Lynn I. Clinical Guidelines: Care of Children with Cystic Fibrosis. UK: Royal Brompton and Harefield Hospital, NHS Trust Foundation; 2023.